1. Field of the Invention
The present invention relates to a control apparatus for an electric actuator, which makes it possible to preferably protect a rotary driving source for driving the electric actuator.
2. Description of the Related Art
In general, when an industrial robot of the installation type is used, a base is fixed by using, for example, bolts. The operation of the robot is stopped by detecting excess current when any forcible pushing or collision occurs at the end of the robot due to any mistake in relation to interlock or the like. That is, it is principally intended that the robot and/or a workpiece is prevented from breakage or destruction by detecting the excess current for the industrial robot of the installation type. In this case, the positional deviation of the robot is not taken into account.
In view of the above, Japanese Laid-Open Patent Publication No. 2002-66969 discloses prevention of an automatic or unmanned transport vehicle from being lifted up or raised upwardly even when the end of a robot arm causes any forcible pushing or collision against the equipment.
That is, Japanese Laid-Open Patent Publication No. 2002-66969 discloses that the end of the robot arm is moved in response to the control of the posture and the position in relation to the end of the robot arm, and that a control apparatus executes the restriction of the current supplied to a servo motor for driving a joint of the robot arm when the joint torque applied to the joint of the robot arm reaches a predetermined limiting value.
However, when the technical concept disclosed in Japanese Laid-Open Patent Publication No. 2002-66969 is applied, for example, to an electric actuator for converting the rotary motion of a motor into the rectilinear motion of a slider or the like, it is necessary to provide a control circuit and a detector such as a resolver and an encoder in order to control the operation speed and the position of the slider. As a result, production cost may be high.